Newly discovered fast radio burst challenges what astronomers know about these powerful astronomical phenomena

Newly discovered fast radio burst challenges what astronomers know about these powerful astronomical phenomena

A newly discovered rapid radio burst has some unique properties that simultaneously give astronomers important clues as to what may be causing these mysterious astronomical phenomena while questioning one of the few things that scientists thought they knew about these powerful flares, which I and my colleagues describe in one new study in the wild on June 8, 2022.

Fast radio bursts, or FRBs, are extremely bright pulses of radio waves coming from distant galaxies. They emit as much energy in a millisecond as the sun does for many days. Researcher here at West Virginia University discovered the first FRB as early as 2007. In the last 15 years, astronomers have discovered about 800 FRB, with more are discovered every day.

When a telescope captures an FRB, one of the most important properties of scientists is looking at something called dispersion. Dispersion is basically a measure of how extensive a FRB is when it reaches the earth.

The plasma between stars and galaxies causes all light – including radio waves – to slow down, but lower frequencies feel this effect more strongly and slow down more than higher frequencies. FRB contains a range of frequencies, so the higher frequency light in the cut hits the earth before the lower frequencies, causing the scattering. This makes it possible for researchers use dispersion to estimate how far from the earth an FRB originates. The more extensive an FRB is, the more plasma the signal must have passed, the farther away the source must be.

A diagram with six panels, each showing a nail in a winding line and a shaded frequency diagram.
The upper part of this diagram shows six peaks in radio wave brightness which are six bursts from FRB190520. The lower half shows the frequency range for each individual burst. Niu, CH., Aggarwal, K., Li, D. et al., CC BY

Why it matters

The new FRB was discovered by me and my colleagues is called FRB190520. We found it using Five hundred meters spherical telescope with aperture In China. An immediately obvious interesting thing about FRB190520 was that it is one of the only 24 repeating FRBs and is repeated much more often than others – producing 75 showers over a period of six months in 2020.

Our team then used Very large array, a radio telescope in New Mexico, to further study this FRB and managed to find the location of its source – a dwarf galaxy about 3 billion light-years from Earth. That was when we began to realize how unique and important this FRB is.

First we found it a persistent, but much weaker, radio signal is transmitted of something from the same place that FRB190520 came from. Of the more than 800 FRB has been discovered so faronly another has a similar sustained radio signal.

Second, since we could determine that FRB came from a dwarf galaxy, we could determine exactly how far away that galaxy is from Earth. But this result did not make sense. To our great surprise, the distance estimate we made using the spread of FRB was 30 billion light-years from Earth, a distance 10 times greater than the actual 3 billion light-years to the galaxy.

Astronomers have only been able to determine the exact location – and therefore the distance from Earth – of 19 other FRB sources. For the rest of the approximately 800 known FRBs, astronomers have to rely on scattering alone to estimate their distance from Earth. For the other 19 FRBs with known locations, the estimated distances from scattering are very similar to the actual distances to their source galaxies. But this new FRB shows that estimates that use dissemination can sometimes be inaccurate and throw many assumptions out the window.

An image that shows distant bright spots of stars and galaxies.
FRB190520 came from a small dwarf galaxy 3 billion light-years away, marked by the crosshair in the larger insert with the exact location of the FRB source in the circle in the smaller image. Niu, CH., Aggarwal, K., Li, D. et al., CC BY

What is still not known

Astronomers in this new field still do not know what exactly produces FRBso every new discovery or information is important.

Our new discovery raises specific questions, including whether persistent radio signals are common, what conditions produce them, and whether the same phenomenon that produces FRB is responsible for transmitting the persistent radio signal.

And a big mystery is why the spread of FRB190520 was so much greater than it should be. Is it due to something close to FRB? Was it related to the persistent radio source? Does it have to do with the thing in the galaxy where does this FRB come from? All these questions are unanswered.

What comes next

My colleagues will focus on studying FRB190520 with a variety of telescopes around the world. By studying the FRB, its galaxy and the space environment that surrounds its source, we hope to find answers to many of the mysteries it revealed.

More answers will also come from other FRB deposits in the coming years. The more FRB astronomers catalog, the greater the chance of discovering FRBs with interesting features that can help complete the puzzle with these fascinating astronomical phenomena.

The conversation

Kshitij Aggarwalaffiliate researchers in astronomy and astrophysics, West Virginia University

This article is republished from The conversation under a Creative Commons license. Read original article.


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